Hope someone can help me. I just finished rebuilding the steering column in my 1988 5.7 liter auto IROC. A couple of days after completion this buzzer started to go off. If the ignition is off it buzzes all the time. If I wiggle the ignition cylinder there is a tiny spot where if will stop. If I turn the key to the on position or start the engine and pull the seat belt out it stops...........I'm confused.

 

I'm pretty sure that means there is a short in the circuit that tests to see whether the key is in. Not 100 Percent tho.
edit- Does the buzzing stop when you shut the door?

 

It may need a new ignition key cylinder. You could yank the "chime unit" (the book calls it the "audible alert" unit), it's in the convenience center underneath the dash just to the right of the steering column. It has some tabs that you have to release then you can pull the whole convenience center down and it will have several relays, fuses, and the chime unit (the big black box). They all just plug in so you can just pull it straight out. That'll at least quiet the thing until you can get the problem fixed.
This could also let you test to see if the problem is the chime unit itself, maybe swap it out with a known good one.
But I believe most of the time this problem is the contacts in the ignition.